Re: "It's actually quite high on our list of priorities but we are so busy with new features that we just haven't gotten there yet. Please check back soon!"

Define "high". Since I joined in November 2016 I've only seen trivial "new features" implemented. This one is essential. Look: I don't really care if the "arpeggio" sounds, and I don't even care if I have to drag it down to the lower staff (or up to upper staff) manually, but it's virtually impossible to write piano music without rolls that extend from one hand to the other. How can that possibly be difficult? Send me your source code, and I'll make the change myself.

We are honestly really sorry to lose you over this! It's actually quite high on our list of priorities but we are so busy with new features that we just haven't gotten there yet. Please check back soon!

I was attempting to do this right now, and was a bit disappointed it could not be done. I was optimistic when I was able to drag the slur originally created for some notes on the treble staff to cover notes in the bass staff, but during playback the bass staff notes were not played legato.

So when you write for piano you sometimes want to slur switching between hands. (Ex. Cantabile et Presto piano part first measure) I feel that this is a small but important feature that a lot of people can benefit from.

All I have to say about this is another music notation site, Musescore has this feature and this has been a tempting reason for me to switch over. As a poster mentioned this is an absolutely integral part of piano music notation and many of my scores on here call for it.

This happens in harp music, too, especially with glissandi (I have a part with a gliss. from C3 to G6). It'd also be nice if a grand staff could be set to work like it does in piano and harp music, with Middle C directly between the staves - and ties, glissandi, etc. moving from one to the other, instead of confined to one OR the other.